Structure of a nonadecapeptide of the fifth EGF domain of thrombomodulin complexed with thrombin.
Structure of a nonadecapeptide of the fifth EGF domain of thrombomodulin complexed with thrombin.
复制标题
与凝血酶复合的血栓调节蛋白第五个 EGF 结构域的九肽结构。
DOI：
10.1021/bi00250a006
复制
发表时间：
1994
期刊：
影响因子：
2.9
通讯作者：
Sadler,JE
中科院分区：
文献类型：
--
作者：
Mathews,II;Padmanabhan,KP;Tulinksy,A;Sadler,JE
摘要：测定了人血栓调节蛋白第五表皮生长因子(EGF5)结构域中的非十八肽与人D-PheProArg-a-凝血酶的复合物的晶体结构。该肽对应于血栓调节蛋白的氨基酸残基Glu408-Glu426，并含有EGF5的第三个二硫键环及其与EGF6的连接物。该结构在3.0A分辨率下进行了优化，I？值为0.146。在不对称单元中有两个凝血酶分子，晶体中的结构是2：1的凝血酶复合体。该肽的折叠与因子Xa的EGF2的第三个二硫键环(RMSA=1.0A)密切对应。该多肽被挤压在两个凝血酶分子的界面电阳性纤维蛋白原识别外区之间。由于该肽共有7个天冬氨酸和谷氨酸残基，与凝血酶的主要结合作用是静电作用。一个主要的疏水结合，在这种明显的静电环境中具有高度的方向性，涉及多肽的TyrlleLeu三联体和一个凝血酶分子的Phe34、Leu65、Tyr76和Ile82(糜蛋白酶原编号)。该肽的酪氨酸夹在凝血酶芳香环之间，很可能是凝血酶调节蛋白-凝血酶相互作用的特异性的主要来源。两种不同的抗凝机制是通过与细胞表面的接触而触发的。一种涉及表面类肝素分子，其功能是加速抗凝血酶III使凝血酶失活(Rosenberg&Rosenberg，1984)。另一种涉及凝血酶调节蛋白，一种凝血酶结合的细胞表面受体，通过降低凝血酶催化凝块形成的能力，同时将凝血酶转化为有效的蛋白C激活剂，改变凝血酶的大分子特异性(Esmon&Owen，1981；Esmon，1989)。激活的蛋白C通过灭活因子Va和Villa(Nesheim等人，1982)起到抗凝血剂的作用，这两个调节蛋白分别参与因子X和因子IX的激活。凝血酶-血栓调节蛋白-LIN复合体的形成直接抑制凝血酶
Revised Manuscript Received September 26, 1994® abstract: The crystallographic structure has been determined of a complex between a nonadecapeptide from the fifth epidermal growth factor (EGF5) domain of human thrombomodulin and human D-PheProArg-a-thrombin. The peptide corresponds to amino acid residues Glu408—Glu426 of thrombomodulin and contains the third disulfide loop of EGF5 and its linker to EGF6. The structure was refined at 3.0-A resolution to an I?-value of 0.146. There are two thrombin molecules in the asymmetricunit, and the structure in the crystal is a 2: 1 thrombin complex. The foldingof the peptide corresponds closely to the third disulfide loop of EGF2 of factor Xa (rmsA= 1.0 A). The peptideis squeezed between cofacial electropositive fibrinogen recognition exo sites of the two thrombin molecules. Since the peptide has a total of seven aspartic and glutamic acid residues, the principal binding interaction with thrombin is electrostatic. A major hydrophobic association, which is highly directional in such a pronounced electrostatic environment, involves a TyrlleLeu triplet of the peptide and Phe34, Leu65, Tyr76, and Ile82 (chymotrypsinogen numbering) of one thrombin molecule. The tyrosine of the peptide is sandwiched between the thrombin aromatic rings and is most likely the prime source of the specificity of the thrombomodulin—thrombin interaction.Two distinct anticoagulantmechanisms are triggered by contact with cell surfaces. One involves surface heparin-like molecules that function to accelerate the inactivation of coagulation proteases by antithrombin III (Rosenberg & Rosenberg, 1984). The other involves thrombomodulin, a thrombin-binding cell surface receptor that alters the mac-romolecular specificity of thrombin by decreasing its ability to catalyze clot formation while at the same time converting thrombin into a potent protein C activator (Esmon & Owen, 1981; Esmon, 1989). Activated protein C functions as an anticoagulant by inactivating factors Va and Villa (Nesheim et al., 1982), two regulatory proteins of the coagulation pathway that participate in the activation of factors X and IX, respectively. Formation of the thrombin—thrombomodu-lin complex directly curtails the capacity of thrombin to